Although the average amount of DRAM shipping with PCs has continued to grow since its peak in 2007, the annual increases are getting smaller, which indicates a historical drop in what PCs need, according to a report by IHS iSuppli.

While the amount of DRAM in PCs grew by 56.1% in 2007 and 49.9% in 2008, it's been slipping for six years now, IHS iSuppli said. This year's increase will be only 17.4%, four percentage points less than in 2012.

The rate of growth in PCs, both desktops and laptops, is expected remain comparatively low, rising by 21.3% next year and then remaining in the 20% range until at least 2016, IHS's report states.

"For a generation, PCs have steadily improved their hardware performance and capabilities every year, with faster microprocessors, rising storage capacities and major increases in DRAM content," Clifford Leimbach, memory analyst at IHS, said in a statement. "These improvements -- largely driven by rising performance demands of new operating system software -- have justified the replacement cycle for PCs, compelling consumers and businesses to buy new machines to keep pace."

As the pace of DRAM use has slowed, it reflects "the maturity of the PC platform" as well as a dramatic change in notebook computers as system manufacturers adjust to the rise of smartphones and media tablets, Leimbach said.

The adoption of ultrathin notebooks such as the MacBook Air and Intel's ultrabooks means more focus on increased battery life so the systems can remain competitive with tablets. As a result, DRAM chips must share limited space on the PC motherboard with other semiconductors that control a notebook's other functions. Incorporating more DRAM can limit other notebook capabilities, IHS stated.

"Notebook makers have shown a willingness to limit increase in DRAM on their systems, rather than sacrifice the thin form factor or eschew other features," iHS said.

PCs historically have dominated DRAM consumption. However, starting in the second quarter of 2012, PCs accounted for less than half of all DRAM shipments, and for the first time didn't use 50% or more of the leading type of semiconductor memory. The trend is partly due to slowing PC sales, combined with the deceleration in DRAM use in the systems.

For desktops, the maturity of hardware and operating systems means DRAM is now less of a bottleneck, tempering the need to increase it to boost system performance.

Unlike previous releases, the latest version of Windows, for example, has not required a DRAM increase.

"All told, PCs no longer need to add DRAM content as much as they did in the previous times, when failure to increase memory content in either desktops or laptops could have resulted in a direct impediment to performance," Leimbach said. "The new normal now calls for a different state of affairs, in which DRAM PC loading won't be growing at the same rates seen in past years."